Ah ha!! Problem solved!!!   It's indeed because I don't use SSH connect to the manager node. (I connect to another instance that created by my own, I didn't notice that)   So when I try to connect to the manager node, there is no public DNS, the way to solve it shown below: Go to console.aws.amazon.com Go To Services -> VPC Open Your VPCs select your VPC connected to your EC2 and Edit Summary ---> Change DNS hostnames: to YES   Then you'll find all the instance have public DNS now! find the manager node one, then it works! ... View more